Power selection device



July 1, 1969 E. P. HOFFMAN 3,453,403

POWER SELECT [ON DEVICE Filed Aug. 18, 1966 Sheet of 2 O as 90K) n2 usv I ELDON P HOFFMAN INVENTOR B) BUC/(HOR/V, BLORE, KLAROU/ST a SPAR/(MAN ATTORNEYS E. P. HOFFMAN July 1, 1969 POWER SELECTION DEVTCE I Sheet .2 012 Filed Aug. 18, 1966 ELDON P. HOFFMAN BUG/(HORN, BL ORE, KL AROU/S T a SPAR/(MAN ATTORNEYS United States Patent US. Cl. 200-51 14 Claims ABSTRACT OF THE DISCLOSURE A power selection device for mounting on an electrical apparatus includes an insulating base member provided with a plurality of sockets into which movable plug means are selectively inserted for completing power connections in the apparatus. A removable cover carries connection means including a fuse through which the aforementioned sockets are empowered when the cover is in place. Also, the cover when in place is closely spaced from the base member at a distance from the plug means preventing removal thereof from the sockets. Each plug means includes an indicator pin which protrudes through one of a plurality of apertures in the cover for indicating the position of the plug means.

This invention relates to a power selection device and particularly to such a device for safely modifying the operating voltage of an electrical apparatus without necessitating internal wiring changes.

Electrical apparatus typically requires a supply voltage having a reasonably specific value in order for the apparatus to operate properly. While some electrical apparatus can be altered internally for selectable operation at more than one line voltage, such alteration usually involves connection changes within theapparatus, or possibly substitution of components. Alterations of this type are not only time consuming but require the services of one familiar with the wiring of a particular apparatus before the change can be properly made. Also, the changeover procedure may endanger the person performing the wiring change if voltage is present or can be present across the circuit wherein the change is necessary.

It is accordingly an object of the present invention to provide an improved power selection device for conveniently adapting an electrical apparatusfor operation at different line voltages.

It is another object of the present invention to provide an improved power selection device whereby the line voltage requirements for an electrical apparatus may be conveniently predetermined and altered without danger to the operator.

It is another object of the present invention to provide an improved power selection device for conveniently, economically and safely changing the operating voltage of an electrical apparatus from one nominal value to another, as well as providing adjustment for undervoltage and overvoltage conditions.

In accordance with the present invention, a power selection device is provided with selection means for altering the power connection thereof. The device is also provided with a removable cover that normally prevents such alteration. The cover cooperates with the device for completing the power connections thereto when such cover is in place, but removal of the cover disconnects the device such that a change in selection can then be performed without danger. The selection means also desirably includes indication means discernible from outside the cover whereby the apparatus rating can conveniently be ascertained.

In accordance with an embodiment of the present inven- 3,453,403 Patented July 1, 1969 tion, a voltage selection device comprises an insulated base having a plurality of electrical socket terminals for receiving plug means cooperable with the socket terminals. The plug means interconnect the socket terminals in various wiring patterns for determining the input voltage of the apparatus. The plug means may be partially removed and changed to accomplish a different wiring arrangement only so long as the device cover is removed. Removal of the cover disconnects the source of power so that changes in the plugging arrangement can then be accomplished safely. In accordance with a preferred form of the, invention, the cover carries one or more fuses for completing the power circuit to the electrical apparatus when the cover is secured in place. The fuses then provide not only usual protection but a switching action as well.

The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, both as to organization and method of operation, together with further advantages and objects, may best be understood by reference to the following description, taken in connection with the accompanying drawings wherein like reference characters refer to like elements and in which:

FIG. 1 is a front view of a power selection in accordance with the present invention,

FIG. 2 is a schematic diagram illustrating inter connection of the power selection device according to the present invention, and

FIG. 3 is a disassembled view of a power selection device in accordance with the present invention.

Referring to the drawings, and particularly to FIGS. 1 and 3, a power selection device according to the present invention comprises a base member 10 secured within an aperture in a metal panel 12 forming the accessible outer wall of an electrical apparatus. The base 10 is positioned in panel 12 for exposing a flat face 14 at a conveniently accessible location, e.g., at the rear of the apparatus. Base member 10 is molded from a suitable insulating dielectric material such as phenol formaldehyde, and supports therewithin a plurality of sockets, numbered 16 through 33. The base member 10 is partially broken away in FIG. 3, illustrating the manner in which the socket terminals are imbedded in the base member, and the manner in which they extend through the base member for connection at the rear thereof to circuitry in the electrical apparatus. A connector or plug 34, for cooperating with the base member, is provided with a pair of U- shaped pins 36 and 38 for selectively engaging certain of the socket terminals in base member 10. Plug 34 is formed of insulating material and is also provided with a shaft 40 receivable within a cylindrical opening 42 in base member 10. Shaft 40 is designed to extend through the base member where it is secured by means of a retaining clamp 44. However, the shaft 40 isof sutficient length between plug 34 and clamp 44 so that plug 34 may be withdrawn from selected socket terminals and turned upon shaft, 40 permitting U-shaped pins 36 and 38 to be plugged into other socket terminals. In the position shown for plug 34 in the drawing, U-shaped pin 36 will connect socket terminals 18 and 20 when the plug is completely inserted. Also, U-shaped pin 38 will join socket terminals at 19 and 21. However, when the plug is removed and rotated 180, it may be reinserted with U- shaped pin 38 joining socket terminals 16 and 18. At the same time, U-shaped pin 36 will connect socket terminals 17 and 19. As will hereinafter become more evident, this change in the position of the plug conveniently rewires the electrical apparatus from volt operation to 230 volt operation. Thus, the plug and socket arrangement comprises a voltage selection means. The clamp 44 prevents loss of the plug.

The device according to the present invention is also provided with a second plug 46 having a pair of U-shaped pins 48 and 50 cooperable with socket terminals 24-33. Plug 46, which is also formed of insulating material, is provided with a shaft 52 slidably receivable within slot 54 in base member 10. Shaft 52 is secured on the reverse side of base by means of retaining clamp 56. However, plug 46, like plug 34, is removable to an extent such that the plug may be withdrawn from certain socket terminals and moved to engage other socket terminals. For example, in one position of plug 46, U-shaped pin 48 electrically connects socket terminals 28 and 31, While U- shaped pin 50 joins socket terminals 22 and 25. If desired, the plug 46 may be withdrawn and shaft 52 moved laterally along slot 54 so that U-shaped pin 48 is plugged into socket terminals 29 and 32. At the same time, U-shaped pin 50 connects socket terminals 23 and 26. In a third position of plug 46, pin 48 joins socket terminals 30 and 33 while pin 50 connects socket terminals 24 and 27. As hereinafter more fully described, the socket terminals of base member 10- may be connected with the electrical apparatus such that shifting of plug 46 from one position to another selects a given range of operating voltage for the electrical apparatus.

Base member 10 includes wells 58 and 60 conveniently indented from the surface 14 of the base member. Each of these wells includes a pair of fuse clips for receiving a cartridge fuse. In FIG. 3, one set of fuse clips 62-64 is illustrated in a broken-away section of base member 10. These fuse clips are connected with the electrical apparatus such that no line voltages are present across socket terminals unless fuses are inserted therein.

The device according to the present invention also includes a metal cover 70' adapted for mating with the portion of base 10 protruding from panel 12 and specifically the face 14 thereof. Thus, with cover 70 in place, socket terminals 16-33 are enclosed from the front. Cover 70 is securable to base 10 by means of slotted and knurled nuts 74 adapted to engage studs 76 on the base member. When so secured, the edges of cover 70 bear upon and connect to conductive gasket 78 joined to panel 12. Therefore, the base member 10 may be electrically enclosed and shielded against electromagnetic interference by cover 70. Cover 70 not only fits over the protruding portion of base 10, but also encloses plugs 34 and 46 within interior region 72 of the cover. In the fully engaged position of cover 70, plugs 34 and 46 are accommodated within the cover only as these plugs are fully engaged with selected socket terminals. In this manner, the cover secures the plugs in place.

Cover 70 is also provided with a pair of insulated fuse holders 80 and 82 for receiving cartridge fuses 84 and 86 respectively. These fuse holders and the fuses they support are reecivable in wells 58 and 60, and engageable with the fuse clips therewithin, as cover 70 is secured to base member 10. The wiring of the base member is such that no line voltage appears across any of the socket terminals 16-33 except when the cover 70 carrying the fuses 84 and 86 is in place. Thus, removal of the cover 70 removes power from the socket terminals and the plugs 34 and 46 may be repositioned without danger to the individual from line voltages, or immediate danger to the individual from improper positioning of the plugs.

According to another feature of the present invention, plugs 34 and 46 are provided with indicator pins 88 and 90 for disclosing the particular plugged arrangement even though cover 70 is secured in place. Cover 70' includes a plurality of apertures 92-96 for mating with positions of indicator pins 88 and 90 as plugs 34 and 46 are located in various of their selected positions. One example of the indication provided by indicator pins 88 and 90 is illustrated in FIG. 1. Referring to FIG. 1, pin 88 protrudes thr gh per ure 93 indicating hat plug 34 is n a po tion joining socket terminal 19 to 21 and socket terminal 18 to 20. The wiring between the base member 10 and the electrical apparatus is such that these terminals conmeet the apparatus for 115 volt operation. Also, pin on plug 46 protrudes through aperture 96, indicating that socket terminal 28 is joined to socket terminal 31 while socket terminal 22 is similarly connected to socket ter minal 25. In this position, the apparatus is connected to operate in a relatively low voltage range. Since plug 34 is positioned for nominal 115 volt operation, the position of plug 46 will adapt the electrical apparatus for operation near but lower than this value, for example between 90"and 110 volts. Other plugging positions are indicated formedium and high voltage ranges, as well as for 230 volt operation. In addition to an indicating function, pins 88' and 90 also tend to inhibit engagement of cover 70 upon base 10 unless the plugs 34 and 46 are in a proper position and the pins can extend through a pair of the apertures provided.

FIG. 2 is a schematic diagram illustrating power wiring for the present device. The base member 10 is wired to a power transformer 98 of a typical electrical or electronic device. This power transformer includes a secondary winding 100 and a pair of primary windings 102 and 104 having a substantially equal number of turns.. These primary windings are connected in parallel for 115 volt operation of the electrical apparatus, and in series for 230 volt operation.

Power is supplied the windings of the transformer 98 from line cord plug 108 via the power selection device according to the present invention, and power switch sections 106 and 120 which are simultaneously operable. Line fuse 84 is serially inserted between the line cord plug 108 and switch section 120 by way of fuse clip terminals 62' and 64' of fuse clips 62 and 64 respectively. This fuse therefore acts to disconnect the power as the cover 70 is removed. The various socket terminals of base member 10, as coupled by plugs 34 and 46, function to interconnect the transformer windings for operation at various selected voltages.

As illustrated in the drawings, a first terminal of winding 102 is connected to socket terminal 20 as well as to one section 106 of the apparatus power switch. The remaining terminal of switch section 106 is connected to one terminal of line cord plug 108, while the remote terminal 110 of winding 102 is connected to socket terminal 24 on base member 10. Winding 102 is also provided with a pair of intermediate taps 112 and 114 adapting the apparatus for differing input voltages. The tap 112 is connected to socket terminal 23 while tap 114 is connected to socket terminal 22.

Winding 104 includes a terminal 116 coupled to socket terminal 21 and thermal switch 118, the latter being designed to open when the electrical apparatus overheats. Power switch section 120 connects the remote side of thermal switch 118 to terminal 62 of fuse clip 62, while the remote terminal 122 of winding 104 is connected to socket terminal 33 of base member 10. Winding 104 is also provided with a pair of intermediate ta-ps 124 and 126, respectively electrically connected to socket terminals 32 and 31. The remaining fuse clip terminal 64', joined to fuse clip 64, is connected to the opposite terminal of line cord plug 108. Line cord plug 108 is also conveniently provided with a grounding pin 128 for connection to apparatus ground.

Base member 10 also includes fuse clip terminals 66 and 68 joined to fuse clips in well 60 and respectively wired to socket terminals 16 and 17. The fuse 86, which isconnected across these terminals when cover 70 is secured in place, is designed to fail at a lower current rating than fuse 84, as hereinafter more fully described.

In electrical operation, the device of the present invention is useful in selecting the nominal operating voltage of the electrical apparatus to which it is connected, as well as in compensating for undervoltage or overvoltage condi ticns. With pl g 34 in he p sit on as illustrated in F G.

3, that is joining socket terminals 19 and 21 and joining terminals 18 and 20, the apparatus is connected for 115 volt ope-ration. With plug 34 in this position, primary windings 102 and 104 are connected in parallel, via socket terminals 18-20 and 19-21 respectively. Transformer 98 is provided with a relatively high turns ratio by this connection. However, with plug 34 reversed, the socket termi nal 17 is joined to socket terminal 19 and similarly socket terminals 16 and 18 are connected. In the latter wiring configuration, primary windings 102 and 104 are connected in series. This series connection is completed through fuse 86 joining terminals 66 and 68. This connection pro vides transformer 98 with a lower turns ratio, equal to substantially half that provided by the previous plugging arrangement. Therefore, a nominal 230 volt rating is achieved.

For indicated line voltage operation, that is, when the line voltage is determined to be close to the selected value of 115 volts or 230 volts, plug 46 may be located in mid-position, joining socket terminal 29 to 32 and socket terminal 23 to 26. With plug 46 in this position, tap 124 of winding 104 and tap 112 of winding 102 are selected and these taps connect the proper number of turns for the nominally indicated voltage operation. However, if an undervoltage condition exists on the line, plug 46 should be shifted to its low voltage position selecting the connection of socket terminal 28 to 31, as well as 22 to 25. In this plugging arrangement, taps 126 and 114 provide a higher turns ratio. On the other hand, if the input line is over nominal voltage, shifting of plug 46 to its high voltage position will select winding terminals 122 and 110 for reducing the turns ratio of transformer 98.

As previously indicated, fuse 84 is a line fuse and is connected via terminals 62' and 64' between the line cord plug and power switch section 120 leading to winding 104 of the transformer. This fuse is designed to carry rated current for 115 volt operation, that is with the primary windings 102 and 104 in parallel. If excess current is drawn through fuse 84, the fuse element will fail and the circuit will be interrupted. However, when plug 34 is positioned for 230 volt operation, rated power for the electrical apparatus will be reached at a considerably lower value of current, i.e., half the value indicated for 115 volt operation. For this reason, fuse 86 is inserted between windings 102 and 104 by plug 34 when 230 volt operation is selected. As hereinbefore indicated, the current rating of this fuse is less than for fuse 84, e.g., approximately half the rating of the latter, and, accordingly, fuse 86 will fail should rated current for 230 volt operation be exceeded. Of course, power is completely removed from across the socket terminals of base member when cover 70 is removed since both fuses are removed at that time.

Thus, the power selection device of the present invention provides a convenient means for selecting connections therein, and operation of electrical apparatus at different line voltages. Therefore, the electrical apparatus need not be manually rewired to operate efficiently on the line voltage available in a given area. Moreover, the instrument is also adapatable to line voltage variation as may occur from time to time. The changes for adapting the apparatus to these variations are easily made by simply changing the plugging arrangement of the device and, since the plugging device is deactivated when the cover is removed and line voltage does not appear across exposed terminals of the device, the plugging arrangement may be changed Without danger to the individual. The device also provides the housing for fuses protecting the electrical apparatus, these fuses simultaneously performing their usual function and that of disconnecting the power.

While I have shown and described a preferred embodiment of my invention, will be apparent to those skilled in the art that many changes and modifications may be made without departing from my invention in its broader aspects. I therefore intend the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

I claim:

1. A power selection device for mounting in connection with an electrical apparatus comprising:

a base member securable to an accessible portion of said electrical apparatus, said base member being provided with selection means electrically interconnected with said electrical apparatus for changing the wiring thereof, said selection means comprising socket means on said base and plug means cooperable therewith for selectably changing said wiring,

a cover means removably securable to said base member for covering said selection means in a predetermined position of said'cover means, said cover means when thus secured to the base member being closely spaced from the base member at a distance from said plug means preventing removal thereof from said socket means,

said plug means including means for ascertaining the position of the plug means from outside the cover when the cover is in said predetermined position, and

means cooperably carried by said base member and said cover means for completing electrical connection to at least ones of said selection means only when said cover means is in said predetermined position and for disconnecting said selection means when said cover means is substantially removed from said predetermined position.

2. A power selection device for mounting on an electrical apparatus comprising:

an insulated base member for receiving a plurality of electrical connections, said base member including a plurality of socket terminals in circuit with the said electrical connections,

plug means cooperable with said socket terminals for interconnecting selected socket terminals in a predetermined wiring pattern,

a removable cover for mating with the said base member, said cover being provided with means for removably securing said cover over said base member, and in close spaced relation with said plug means to prevent removal of said plug means, and

circuit connection means comprising first means in said base member and second means in said cover for completing an electrical circuit therebetween for empowering certain electrical connections to said base member only when said cover is secured to said base member.

3. The device according to claim 2 wherein said cover is electrically conductive.

4. The device according to claim 2, wherein said plug means is provided with an indicator element and said cover is provided with apertures for observing the position of the said indicator element to determine the position of said plug means when said cover is secured to said base member.

5. A device according to claim 2, wherein said first means in said base member and said second means in said cover respectively comprise a fuse clip and a fuse holder brought together when said cover is secured to said base member.

6. A power connection device comprising:

a base formed of insulating material and adapted for mounting on electrical apparatus, and having a plurality of socket means adapted for connection to a source of electric power,

connector means adapted for engagement with said socket means for interconnecting selected socket means in a predetermined wiring pattern, and

a removable conductive cover for covering at least the socket means of said insulated base and the connector means cooperating therewith in a predetermined position of said conductive cover,

said cover carrying means for completing an electric power connection to the socket means of said base when said cover is in said predetermined position relative to said base.

7. The device according to claim 6, wherein said connector means comprises a plug including interconnections for selectively coupling ones of said socket means, and also including a shaft upon which said plug means is both slidable outwardly from said base and rotatable with respect to said base for interconnection with other mating ones of said socket means in selected rotatable positions of said plug.

8. The device according to claim 6, wherein said connector means comprises a plug including interconnections for coupling selected socket means in a first predetermined engaged position, and also including an extension member enabling withdrawal of said plug from said base member for slidable movement of said plug with respect to said base member and selected interconnection with other of said socket means.

9. The device according to claim 6, wherein one said connector means comprises a first plug including interconnections for selectively coupling ones of said socket means, and also including a shaft upon which said plug is both slidable outwardly from said base and rotatable with respect to said base for interconnection with other mating ones of said socket means for changing the voltage operating connection of said electrical apparatus from one voltage level to a substantially different voltage level, and

wherein another said connector means comprises a second plug including interconnections for coupling selected socket means in a first predetermined engaged position, and also including an extension member enabling withdrawal of said plug from said base member for slidable movement of said plug and selected interconnection with other of said socket means for changing the voltage connection of said apparatus within a given range.

10. The device according to claim 6, wherein said connector means includes an indicator pin protruding from said connector means on a side thereof opposite said base, and wherein said cover includes a plurality of apertures for receiving said pin to indicate the selected position of said connector means beneath said cover.

11. The device according to claim 6, wherein said means for completing electrical power connection comprises means in said cover adapted to carry a fuse element for connection to said base for empowering said socket means only when said cover is in said predetermined position.

12. The device according to claim 11, wherein aid cover is also adapted to carry a second fuse element of lower current rating than the first mentioned fuse element for connection with said base,

said electrical apparatus having a power transformer with two primary windings, and

electrical connection means coupled with socket means of said base and cooperable with said connector means for connecting said second fuse element in series with said primary windings in one predetermined higher voltage position of said connector means.

13. A power selection device comprising:

an insulating base member adapted for mounting in an aperture in the metal panel of electrical apparatus', said base member being provided with a plurality of electrical socket means coupled to the power connections of said electrical apparatus,

at least one plug means cooperable with said base member and engageable with said socket means in selectable positions for changing the power connectiohs of said apparatus,

said base member having a well provided with fuse clips which are electrically inserted between a source of power and selected of said socket means,

a conductive cover member for said base and the plug means coopera'ble there-with, said cover member 'being removably securable over said base member from the exterior of said apparatus Where said base member extends through said aperture in said metal panel, said cover member making electrical connection with said panel and holding said plug means in place when secured in position over said base member, and

said conductive cover member having fuse holder means for carrying a fuse into operable connection with said f-use clips.

14. The device according to claim 13, wherein a plug means is provided with an indicator pin, and said cover is provided with plural apertures for receiving said indicator pin when said plug means engages selected of said socket means.

References Cited UNITED STATES PATENTS 1,869,936 8/1932 Griswold 200-133 1,910,686 5/ 1933 Frank 200-133 2792,55 9 5/ 1957 Maberry.

2,874,317 2/1959 Couse 310-71 2,899,521 8/1959 Salomone 200-133 3,084,308 4/ 1963 Porter 200-133 X 3,202,788 7/1965 George 200-133 3,231,767 1/ 1966 Powell.

ROBERT K. SCHAEFER, Primary Examiner.

D. SMITH, JR., Assistant Examiner.

7 US. 01. X.R. 310-71; 33942 

